When "adjusting" a `WI.Breakpoint` (e.g. removing and then re-adding with a different
configuration), make sure to only re-add the `WI.Breakpoint` to the `WI.Target` it was just
removed from, rather to all `WI.targets`.

Since we iterate over `WI.targets` in both `WI.DebuggerManager.prototype._setBreakpoint` and
`WI.DebuggerManager.prototype._removeBreakpoint`, we ended up iterating `WI.targets` twice.

Each time the `WI.Breakpoint` is removed from a `WI.Target`, pass the `WI.Target` to the
`callback` given to `WI.DebuggerManager.prototype._removeBreakpoint`, so that the eventual
call to `WI.DebuggerManager.prototype._setBreakpoint` can reuse it as the `specificTarget`,
instead of iterating `WI.targets` (meaning we only iterate it once).